🐛 Incorrect vertical text alignment in NumberBox when no suffix is present

[diluculo]

Describe the bug
The text input shows incorrect vertical alignment when NumberBox has no suffix widgets (e.g., when ClearButton = false and mode = SpinButtonPlacementMode.none). The text appears slightly shifted upward compared to the focused state, creating an inconsistent appearance.

To Reproduce
Steps to reproduce the behavior:

1. Create a NumberBox with the following configuration:

   NumberBox(
     clearButton: false,
     mode: SpinButtonPlacementMode.none,
     // ... other properties
   )

2. Observe the text alignment in both focused and unfocused states
3. Notice the text is not vertically centered when unfocused

Expected behavior
Text should remain vertically centered in both focused and unfocused states

Screenshots

Additional context
This issue appears to be related to #1027, where TextBox's vertical alignment depends on the presence of decorations:

TextAlignVertical get _textAlignVertical {
  if (widget.textAlignVertical != null) {
    return widget.textAlignVertical!;
  }
  return _hasDecoration ? TextAlignVertical.center : TextAlignVertical.top;
}

When NumberBox has no suffix widgets, no decorations are present, causing the alignment to default to TextAlignVertical.top. If this behavior is not intentional, it would be better to modify this logic to maintain consistent vertical centering, especially for NumberBox use cases.

Simple solution by directly setting textAlignVertical in NumberBox:

final child = TextBox(
  key: _textBoxKey,
  // ...
  textAlign: widget.textAlign ?? TextAlign.start,
  textAlignVertical: TextAlignVertical.center,  // This ensures consistent centering
  // ...
);